I've always interpreted this movie to be about destiny. Forrest Gump suffers from borderline mental retardation, which would destine him to a mediocre life. However, he defies this destiny and instead does best with the hand he's dealt. He influences Elvis and Lennon, becomes a war hero, meets 3 presidents, becomes a world famous ping pong player, ect. Meanwhile, the lady who drives the school bus remains a bus driver throughout the movie, despite being dealt a much better hand in life than Forrest. So the movie shows that there isn't really such thing as destiny; what people accomplish in life isn't predestined at birth.

Also, when Forrest speaks at Jenny's tomb, he says "Jenny, I don't know if Momma was right or if, if it's Lieutenant Dan. I don't know if we each have a destiny, or if we're all just floating around accidental-like on a breeze, but I, I think maybe it's both. Maybe both is happening at the same time." The feather floating around in the breeze and the famous quote "life is like a box of chocolates, you never know what you're gonna get" both allude to chance.

TDLR; I think Forrest Gump's theme is defying destiny. Anyone else have any other interpretations?

As a chap studying Film and TV within the media I chose this as my film studies case study. And you have summed up my entire essay in a short paragraph. I applaud you for your consideration into the film and the way you've placed it out is incredible.

I also stepped into Forests ability to look past social stereotypes, not because he didn't know any better but because h understood the role of being different. Like as he thinks the "Coons" are Raccoon's and not the original term the young Caucasian meant to *******.

how about we all have a destiny, a place were meant to go, but we get there however we choose like a feather in the wind. its a combination of lt.dan and mama's. and even tho the feather flew all sorts of places it still ended up where it was meant to be at the end.

I was going to say overcoming great odds, but you kind of beat me to it. Destiny is the greatest odd, it's the invisible looming beast that hovers over you making sure that you follow a specific life path. Sure, some break away from it and become amazing people but most trudge along under it and don't deviate far away.
In Forest Gump, though, it almost seems like he was too stupid to follow the path. Not in a bad way or anything, just that he saw where his life was going and chose not to be a part of it. He saw the town he lived in, the bullies that picked on him, the people that called him simple and instead of just keeping to himself and going along with it, he leaves. Like an animal in pain, he walks away from the source and finds himself where as most people would have just accepted the hand they were dealt and not done anything to change it.
TL;DR: Forest Gump had an amazing life because he was too stupid to understand why everyone else was so mundane.